1. Field of the Invention
The present invention is directed to an x-ray diagnostics installation having a primary radiation diaphragm disposed in the beam path of an x-ray tube, wherein the x-rays attenuated by an examination subject are processed by an image intensifier video chain which includes an image memory.
2. Description of the Prior Art
Primary radiation diaphragms are used in x-ray diagnostics installations to blank portions of the radiation image for reducing stray radiation and for reducing the image brightness. Various types of primary radiation diaphragms are known, such as contour diaphragms, semi-transparent contour diaphragms, finger diaphragms having specific profile absorptions adapted to the subject, etc.
A primary radiation diaphragm is disclosed in German Patent 1 800 879 for use in x-ray examination equipment, the primary radiation diaphragm being formed by two semitransparent diaphragm plates. These diaphragm plates can be adjusted in the transillumination image with operating elements, until they assume a desired position. As a result, however, the attending personnel as well as the examination subject are exposed to undesired, additional radiation because the adjustment of the diaphragm does not form a part of the actual diagnostic exposure.